Newmark then attended graduate school at the University of Illinois at Urbana–Champaign, where he worked under Hardy Cross, Harold M. Westergaard, and Frank E. Richart.

He served as Chairman of the Digital Computer Laboratory of the university from 1947 to 1957 and in 1956 he was appointed head of the Civil Engineering Department and held the position until 1973.

Newmark held many important leadership positions and the reputation of the longest tenure on the University Research Board.

Newmark was the advisor or coadvisor of the following students who completed their Ph.D. in Civil Engineering, Graduate College, University of Illinois at Urbana–Champaign:[1] During World War II Newmark consulted for the National Defense Research Committee and the Office of Scientific Research and Development, for which in 1948 he received the President's Certificate of Merit.

He served on numerous Department of Defense boards and panels, with major contributions to the Minute Man and MX missile systems.

The method is still widely used in numerical evaluation of the dynamic response of structures and solids, such as in Finite element analysis.

Throughout his career Newmark developed a simple, yet powerful and widely used method for analyzing complex structural components and assemblies under a variety of conditions of loading and for calculating the stresses and deformations in soil beneath foundations.

Since Newmark had done numerous studies on the effect of earthquakes on structures, he had the ideal background to tackle such a revolutionary feat.

His work was acknowledged with an invitation to deliver the 5th Rankine Lecture of the British Geotechnical Association, entitled Effects of earthquakes on dams and embankments.